At present there are known rolling contact bearings having a gauging device which supplies a signal carrying information as to movement and/or position of one of the two races of a bearing relative to the other one. Such gauging devices are comprised of a moving pulse generator and a stationary sensor. The pulse generator member, known in the field as impulse ring, is fixed for rotation with the rotating race of the bearing. The pulse generator is usually a toothed or magnetized ring mounted to the member to be kept under control. The sensor, which is usually a Hall effect sensor, is installed onto a fixed part so as to operatively face the toothed or magnetized portion of the impulse ring, near to it or at a preset distance therefrom.
Although the above cited devices give satisfactory performances, they have a limit concerning the rate of pulses per revolution they are able to supply. This turns out to be a limit to the number and/or kind of information available by means of that particular kind of gauging device.
Another inconvenience encountered with known kinds of gauging devices is that dirt which inevitably tends to deposit on their components may jeopardize correct operation thereof over time. Furthermore, these devices are not suited to work under high temperature conditions, whereby they cannot be used for some applications.
In addition, for example where the bearing is applied to the wheel hub of a vehicle, the high magnetic fields generated by a conventional gauging device will attract metal particles from the vehicle brakes with the result that these particles will accumulate on the bearing.
A further drawback lies in that magnetic impulse rings and Hall effect sensors are rather costly.